Sonar devices that transmit sound waves have been used previously to obtain information about underwater articles, including fish, structures and obstructions, and the bottom. The sound waves travel from a transducer mounted to a bottom surface of the vessel through the water. The sound wave transmits from the sonar devices in diverging patterns. The sound waves contact underwater articles, which create return echoes. The transducer receives the return echoes and the sonar device analyzes the received echoes. A display device displays representations of the received echoes, for locating fish and other underwater articles.
The assignee of the instant application provides and has taught sonar imaging systems that are coupled to the watercraft to provide side scan images. Such systems include sonar imaging systems mountable to a motor (such as a trolling motor), a transom of the watercraft, or to the hull of the watercraft. These provide sonar imaging systems operable at multiple resonant frequencies for optimized performance at varying bottom depths. The teachings of such systems include those in U.S. Pat. No. 7,652,952 entitled, “Sonar Imaging System For Mounting To Watercraft”, U.S. Pat. No. 7,710,825 entitled, “Side Scan Sonar Imaging System With Boat Position On Display”, U.S. Pat. No. 7,729,203 entitled, “Side Scan Sonar Imaging System With Associated GPS Data”, and U.S. Pat. No. 7,755,974 entitled, “Side Scan Sonar Imaging System With Enhancement”, the teachings and disclosures of which are hereby incorporated in their entireties by reference thereto.
In conventional sonar imaging systems, the target, or underwater object, is located using one of several ways. In typical side-scan imaging arrangements, the target is indicated as being on a particular side of the boat, depending on which side-scan sonar beam contacts the target. In some multi-beam configurations, a sonar transmitting element and one or more sonar receiving elements are all elements are pointed the same direction. Complex calculations and time shifting are used to artificially angle the array to locate the target at a particular location with respect to the transducer elements. An interferometric arrangement uses phase data from two or more sonar receiving elements and complex calculations to locate a target. This method tends to be processor-intensive.
Embodiments of the present invention pertain to improvements in the state of the art with respect to sonar imaging systems. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.